Soft grippers based on dielectric elastomer actuator (DEA) are usually too flimsy to perform the task of pick and place on a heavier object given their low payload capacity. This work developed a new design of DEA unimorph consists of a flexible frame holding at a DEA on the discrete support by a stiffer spine-like flexure of 380μm thick Polyvinyl chloride (PVC) sheet. It finds an equilibrium of curling up when the DEA's pre-stretch is partially released; it can electrically unfolds upon a voltage application. This dielectric elastomer unimorph of 3 grams produced a maximum voltage induced bending of close to 90° and a maximum voltage-induced blocked force of up to 168mN. Given their higher stiffness and large actuation, these 3-D shaped and strengthened DEA unimorphs can make stronger grippers for passive grasping and active pinching.
Magnet filler–polymer matrix composites (Magpol) are an emerging class of morphing materials. Magpol
composites have an interesting ability to undergo large strains in response to an external magnetic field. The
potential to develop Magpol as large strain actuators is due to the ability to incorporate large particle loading
into the composite and also due to the increased interaction area at the interface of the nanoparticles and the
composite. Mn-Zn ferrite fillers with different saturation magnetizations (Ms) were synthesized. Magpol
composites consisting of magnetic ferrite filler particles in an Poly ethylene vinyl acetate (EVA) matrix were
prepared. The deformation characteristics of the actuator were determined. The morphing ability of the Magpol
composite was studied under different magnetic fields and also with different filler loadings. All films exhibited
large strain under the applied magnetic field. The maximum strain of the composite showed an exponential
dependence on the Ms. The work output of Magpol was also calculated using the work loop method. Work
densities of upto 1 kJ/m3 were obtained which can be compared to polypyrrole actuators, but with almost double
the typical strain. Applications of Magpol can include artificial muscles, drug delivery, adaptive optics and self
healing structures. Advantages of Magpol include remote contactless actuation, high actuation strain and strain
rate and quick response.